JPH07154067A - Insulating adhesive layer structure for metal based board - Google Patents

Abstract

PURPOSE:To improve the intimate contact between a conductor and an insulating adhesive layer by providing a specific interface adhesive layer at the interface between the insulating adhesive layer and a conductor wiring layer. CONSTITUTION:At least one conductor wiring layer 1 is provided and an insulating adhesive layer 4 is formed of a resin containing an inorganic powder between a base metal plate 5 and the conductor wiring layer 1. In such insulating adhesive layer structure for metal base board, an interface adhesive layer 3 containing 10wt.% or less of inorganic powder having the particle size of 1mum or less is provided at the interface between the insulating adhesive layer 4 and the conductor wiring layer 1. For example, a resin principally comprising an epoxy resin is added with alumina powder to provide an insulating adhesive layer 4 which is then applied, before being cured, with a varnish of resin having identical composition but containing no inorganic powder thus forming an interface adhesive layer 3 of 10mum thick. The interface adhesive layer 3 is placed on a base metal plate 5 of Al and a copper foil 1 of 70mum thick having a roughened face 2 as coarse as 15mum is applied thereto and hot pressed thus obtaining an insulating adhesive layer structure for metal baseboard.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an insulating adhesive layer for a metal base substrate used for electronic parts.

[0002]

2. Description of the Related Art In recent years, in order to meet the demands for miniaturization and high functionality of electronic equipment products, the high integration and high density mounting of ICs used for electronic parts such as so-called hybrid ICs have made it possible to reduce the board size. The calorific value per unit area tends to increase. Therefore, the dissipation of generated heat has become an important issue in design. Therefore, in place of the conventional printed board such as a so-called glass epoxy board, the use of a metal base board excellent in heat dissipation is increasing. The insulating adhesive layer of this substrate has a structure in which a high thermal conductive filler is uniformly dispersed in a resin, as disclosed in JP-A-60-7195. For example, as shown in FIG. 3, a base metal plate 5 is arranged on one surface of the insulating adhesive layer 4, and a conductor copper foil 1 having a roughened surface 2 is arranged on the other surface, and thermocompression molding is performed. It is a thing.

[0003]

In the above-mentioned insulating adhesive layer structure, when the inorganic powder contained in the adhesive layer exists at the interface between the conductor and the base metal plate, local adhesion cannot be secured, There is a problem in that the variation and the peeling strength of the conductor become low. Further, when there are defects such as scratches and protrusions on the surface of the base metal plate, bubbles are generated in the defective portion and its periphery in the lamination, and the withstand voltage of the substrate is lowered. The present invention has been made in view of the above problems, and provides an insulating adhesive layer structure for a metal base substrate in which the adhesion between the conductor and the insulating adhesive layer is improved.

[0004]

SUMMARY OF THE INVENTION The present invention comprises at least one
Insulating adhesive layer structure for a metal base substrate, which has an insulating adhesive layer made of resin containing inorganic powder between the base metal plate and the conductive wiring layer, The present invention relates to an insulating adhesive layer structure for a metal base substrate, which is provided with an interface adhesive layer having an inorganic powder content of 1 μm or less of 10% by weight or less at the interface between the adhesive layer and the conductor wiring layer. In the present invention, the interfacial adhesive layer is formed by forming a part (surface) of the insulating adhesive layer into a layer having a small amount of inorganic powder, but this term is used for convenience. Aluminum, copper, iron or the like is used as the base metal plate, and copper foil is usually used as the conductor foil for the conductor wiring layer. The surface of the conductor foil in contact with the insulating adhesive layer is formed with a roughened surface in order to improve the adhesiveness. As the inorganic powder, one having high thermal conductivity having a thermal conductivity of 10 W / m · K or more at room temperature is preferably used, and a typical one is alumina powder.

The resin for the interface adhesive layer and the insulating adhesive layer may be any material as long as it has electrical, mechanical and thermal characteristics necessary for a substrate used for electronic parts and can ensure reliability. Although not particularly limited, for example, epoxy is used. The interface adhesive layer and the insulating adhesive layer are preferably made of the same resin. When the content of the inorganic powder of 1 μm or less in the interfacial adhesive layer exceeds 10% by weight, the inorganic powder enters the roughened surface of the conductor foil of the conductor wiring layer to form the insulating adhesive layer and the conductor wiring layer. Decrease adhesion. The content of the inorganic powder is preferably 5% by weight or less, and particularly preferably the inorganic powder is not contained at all. If particles larger than 1 μm are present as the inorganic powder, the contact between the roughened surface of the conductor foil and the resin is hindered, and the adhesion is lowered.

If the thickness of the interfacial adhesive layer is 50% or more of the length of the foot of the roughened conductor foil of the conductor wiring layer, the adhesion between the insulating adhesive layer and the conductor wiring layer is improved, which is preferable. , 20 more
It is preferable that the thickness be less than or equal to μm because the heat dissipation of the powder can be maintained. Also, at the interface between the base metal plate and the insulating adhesive layer,
By providing an interface adhesive layer similar to that provided at the interface between the conductor wiring layer and the insulating adhesive layer, it is possible to prevent a decrease in the withstand voltage of the substrate due to defects such as scratches and protrusions on the surface of the base metal plate. preferable. The thickness of this interface adhesive layer is preferably 20 μm or less.

[0007]

EXAMPLES Examples of the present invention will be described below. Example 1 75 parts by weight of Epicoat 828 (manufactured by Yuka Shell) of epoxy resin and 25 DEN-431 (manufactured by Dow Chemical)
From 25 parts of epoxidized polybutadiene R45-EPT (manufactured by Idemitsu Petrochemical), 4 parts of curing agent disiamine diamide (manufactured by Nippon Carbide), 0.3 parts of curing accelerator 2PZ-CN (manufactured by Shikoku Chemicals) Alumina powder (Showa Denko, average particle size 3.0μ)
m) 280 parts were added, and further, methyl ethyl ketone (manufactured by Nagase & Co., Ltd.) as an organic solvent was added and well kneaded with a bead mill, and then vacuum deaeration was performed to prepare a slurry. This slurry was applied to a polyester film coated with a release agent by the doctor blade method, and then dried at 120 ° C. for 15 minutes to prepare a 100 μm thick pre-cured insulating adhesive sheet.

This insulative adhesive sheet before curing is used as an insulative adhesive layer 4 as shown in FIG. 1, and a varnish containing no inorganic powder is kneaded by kneading an organic solvent with a resin having the above composition. 4 coated on the non-polyester film side and dried at 120 ° C for 15 minutes, containing no inorganic powder 1
The interface adhesive layer 3 having a thickness of 0 μm was formed. Next, the polyester film of the insulating adhesive layer 4 is peeled off and placed on the aluminum base metal plate 5 having a thickness of 2 mm, and the thickness is 70 μm.
A copper foil 1 having a roughened surface 2 and a foot length of 15 μm is placed on the interfacial adhesion layer 3 and held at 100 ° C. for 10 minutes by a thermocompression bonding press, while applying a pressure of 10 kg / cm ^2. It was held at 200 ° C. for 15 minutes and then naturally cooled to obtain an insulating adhesive layer structure for a metal base substrate having a single-sided single-layer conductor.

Example 2 The polyester film of the insulating adhesive layer having the interfacial adhesive layer prepared in Example 1 was peeled off, and the peeled surface of Example 1 was peeled off.
Apply a varnish containing no inorganic powder with the same composition as
After drying at 0 ° C. for 15 minutes, as shown in FIG. 2, the interface adhesive layer 3 ′ having a thickness of 12 μm is formed on the other surface of the insulating adhesive layer 4.
Was formed. The base metal plate 5 is placed on the interface adhesive layer 3 ', the copper foil 1 is placed on the other interface adhesive layer 3, and thermocompression-bonding pressing is performed in the same manner as in Example 1 below to obtain a metal base of a single-sided single-layer conductor. An insulating adhesive layer structure for a substrate was obtained.

Example 3 Instead of the interface adhesive layer 3'in Example 2, the resin of the same composition as in Example 1 was used on the surface of the insulating adhesive layer 4 of alumina powder having an average particle size of 0.5 μm. 5 parts by weight was added, methyl ethyl ketone was further added, and the kneaded slurry was applied and dried at 120 ° C. for 15 minutes to form an interface adhesive layer having a thickness of 12 μm. An insulating adhesive layer structure for a metal base substrate of a conductor was obtained. Example 4 An insulating adhesive layer structure for a metal base substrate having a single-sided single-layer conductor was obtained in the same manner as in Example 2 except that the surface of the base metal plate was scratched with a diameter and depth of 0.1 mm.

Comparative Example As shown in FIG. 3, an aluminum base metal plate 5 was arranged on one surface of an insulating adhesive layer 4 made of an insulating adhesive sheet in Example 1, and the other surface was treated as in Example 1. The same copper foil was placed, and the same thermocompression bonding was performed as in Example 1 to obtain a single-sided, single-layer conductor insulating adhesive layer structure for a metal base substrate.

[0012]

[Table 1]

One side 1 produced in each of the examples and comparative examples
Regarding the performance of the insulating adhesive layer structure for a metal base substrate of the layer conductor, the peeling strength of the copper foil, the breakdown voltage and the thermal resistance were measured and compared as the performance. The results are shown in Table 1. As is clear from Table 1, the peeling strength of the example is larger than that of the comparative example, the withstand voltage does not decrease due to the area effect even in a large area conductor, and the thermal resistance is the same. .

[0014]

According to the present invention, since the interface between the insulative adhesive layer and the conductor wiring layer does not contain the inorganic powder exceeding 1 μm, the contact area of the resin on the roughened surface of the conductor foil is widened and the effect is increased. In particular, by eliminating the contact between the inorganic powder and the conductor, which does not contribute to the adhesion, it is possible to prevent a local decrease in the adhesion force and ensure the adhesion force for a long time. Further, if the inorganic powder exceeding 1 μm does not exist at the interface between the base metal plate and the conductor wiring layer, it is possible to prevent the withstand voltage of the substrate from lowering due to the defects on the surface of the base metal plate. .

[Brief description of drawings]

FIG. 1 is an enlarged sectional view showing an insulating adhesive layer structure for a metal base substrate according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing an insulating adhesive layer structure for a metal base substrate according to an embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view showing a conventional insulating adhesive layer structure for a metal base substrate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Copper foil, 2 ... Roughened surface, 3 3 '... Interface adhesive layer, 4 ... Insulating adhesive layer, 5 ... Base metal plate

Claims (6)

[Claims] 1. An insulating adhesive for a metal base substrate, which has at least one conductor wiring layer, and an insulating adhesive layer made of a resin containing inorganic powder is formed between the base metal plate and the conductor wiring layer. In the layered structure, the content of the inorganic powder of 1 μm or less at the interface between the insulating adhesive layer and the conductor wiring layer is 10% by weight.
An insulating adhesive layer structure for a metal base substrate provided with the following interface adhesive layer. 2. The insulating adhesive layer structure for a metal base substrate according to claim 1, wherein the interface adhesive layer contains no inorganic powder. 3. The thermal conductivity of the inorganic powder is 10 W / m at room temperature.
The insulating adhesive layer structure for a metal base substrate according to claim 1 or 2, which is K or more. 4. The insulating adhesive layer structure for a metal base substrate according to claim 1, wherein the resin of the interface adhesive layer is the same as the resin of the insulating adhesive layer. 5. The insulation for a metal base substrate according to claim 1, wherein the thickness of the interface adhesive layer is 50% or more and 20 μm or less of the length of the foot of the roughened conductor foil of the conductor wiring layer. Adhesive layer structure. 6. The insulating adhesive layer structure for a metal base substrate according to claim 1, wherein an interface adhesive layer having a thickness of 20 μm or less is formed at an interface between the insulating adhesive layer and the base metal plate.